It is assumed that an access provider and a service provider share physical line information previously in an NGN environment of conventional ITU-T (International Telecommunication Union-Telecommunication Standardization Sector) and TISPAN (The Telecoms & Internet converged Services & Protocols for Advanced Networks). In this case, when a subscriber has access to an access network and network connection authentication succeeds, a subscriber having the same line information is authenticated in a service network without a special authentication key exchange mechanism.
Currently, in documents of ITU-T and TISPAN, SCF (Service Control Function) which takes charge in control, registration, authentication, and authorization of session at a service level needs NACFs (Network Attachment Control Functions) which provides an identification/authentication function of a network level to subscribers who try to access to an NGN service for registration function, to retrieve line information using an IP (Internet Protocol) address as a key in order to obtain physical line information. In normal cases, various NACFs exist in one SCF. However, there is no special mention on which NACF the SCF selects.
According to conventional SCF-NACF bundle authentication, when access authentication that is managed by a specific NACF only for fixed subscribers, succeeds and when a terminal requests a service user ID (Identifier), i.e., PUID (PUblic user ID) or PRID (PRivate user ID), subscribed to SCF-NACF bundle authentication, using an IP address and a realm in which access authentication succeed, service authentication also succeeds. This is because of the following four conditions.
When access authentication succeeds, one IP address and one realm are allocated to a subscriber ID that succeeds access network connection for each line ID. P-CSC-FE (Proxy Call Session Control Functional Entity) obtains an IP and a realm which are a service user ID, from a terminal and obtains a line ID from TLM-FE (Transport Location Management Functional Entity) using the IP and realm. When predetermined SCF and NACF are bundle-subscribed to SUP-FE (Service User Profile Functional Entity), a line ID of the NACF is stored previously for a service user ID (a predetermined line ID is fixed to a fixed subscriber). S-CSC-FE (Service Call Session Control Functional Entity) determines for authentication whether the line ID received from P-CSC-FE and the line ID received from SUP-FE are the same or not.
Furthermore, an NACF-SCF bundle authentication scheme in documents of ITU-T and TISPAN is based on lines and thus can be applied only to a fixed network such as xDSL. Thus, the NACF-SCF bundle authentication scheme cannot be used in WLAN (wireless LAN) or WiBro network in which the terminal is moved.